Remote Terminal Unit
A remote terminal unit (RTU) is a microprocessor-controlled electronic device that interfaces between field devices and SCADA (supervisory control and data acquisition) system by transmitting telemetry data to a master system, and by using messages from the master system to control connected field devices.
An RTU monitors and controls the field digital and analogue parameters and transmits data to and from a SCADA Master Station via available telecommunication medium. Engineer runs software to connect data input streams to data output streams, define communication protocols, and troubleshoot installation problems in the field.
An RTU may consist of simple configuration which normally consist of power supply, processor unit, communication interface and several circuit input and/or output circuits. However, RTU can be very complex on some applications with a bigger database and using redundancy in many aspects.
Modern RTUs typically support programming logic such as IEC 61131-3 programming standard for programmable logic controllers. The logic can be used to automate some actions or/and do some local calculation. Since RTUs may be routinely deployed in gas pipelines and electric grid systems, in hard-to-reach or extreme environments, they are required to operate under harsh conditions, and implement energy-saving measures and It does not have moving parts and uses extremely low power and is often solar powered.